Slot interposer probes are desirable for intercepting signals between an expansion card and a computer's system board and transferring them to a logic analyzer module for analysis. An expansion card is a printed circuit board that is inserted into an expansion slot of a computer's system board. Expansion cards add additional functionality to a computer system. One edge of the expansion card holds the contacts (the edge connector) that fit exactly into the slot. They establish the electrical contact between the electronics (mostly integrated circuits) on the card and on the motherboard.
Demand for more sophisticated computer graphics has led to higher performance video cards, a type of expansion card, that require increased data transfer rates. Presently, PCI Express is the most common interface for graphics cards because of its high-bandwidth data transfer capabilities. Analyzing signals between expansion cards that use PCI Express and system boards to determine what the signals are doing at a logical level is an important part of validating or troubleshooting a computer design. Signal analysis between expansion cards and system boards can also be useful in a service and repair environment to diagnose malfunctions.
The use of slot interposers is known in the prior art. For example, a previous generation slot interposer design 100, which is depicted in FIG. 1, has two mid-bus probe heads 114 attached to a slot board 112. One end of the slot board 112 is inserted into a PCI Express slot in a system board when in use. The other end of the slot board 112 has a PCI Express connector 116 protruding vertically from its upper surface. The PCI Express expansion card 118 to be tested is inserted into the PCI Express connector 116. An optional support bracket 120 secures the PCI Express expansion card 118 to the PCI Express connector 116.
The prior art slot interposer 100 has a number of disadvantages that have become apparent as PCI Express and graphics card technology has advanced. As is shown in FIGS. 2a and 2b, the prior art slot interposer 100 occupies a larger volume of space than does a conventional PCI Express graphics card, which presents a problem with modern computer configurations. The mid-bus probes 114, each of which is about 89 mm in length, make the slot interposer 100 about 178 mm wider than a conventional PCI Express expansion card 118 even before an expansion card 118 is installed. Therefore, the slot interposer 100 has the potential to obstruct other slots on the system board. This prevents expansion cards from being installed adjacent to the slot interposer 100 during testing.
Similarly, the requirement for the expansion card 118 to be plugged in perpendicularly to the slot interposer 100 also has the potential to prevent installation of adjacent cards when the slot interposer 100 is present. When an expansion card 118 is plugged into the slot interposer 100, the slot interposer 100 is nearly 200 mm wide. As graphics card manufacturers have developed technologies that allow up to four graphics cards to run in parallel in adjacent PCI Express slots for increased performance, significant space constraints above the system board exist that prevent the use of the prior art slot interposer 100 for acquiring signals from such system configurations.
Furthermore, the data transfer rates of PCI Express links have increased and are expected to further increase in the future. The version of PCI Express in most common use, PCI Express 1.1 x16, transfers data at 2.5 GT/s in each direction. PCI Express 2.0, which is already appearing in newer systems, doubles this transfer rate. At speeds exceeding 5 GT/s, undesirable capacitive loading because of the length of the mid-bus probes 114 can occur that slows down high-speed signals and/or causes signal reflections.
Therefore, a need exists for a new and improved slot interposer probe that can be used for intercepting signals between an expansion card and a computer's system board and transferring them to a logic analyzer module for analysis. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the slot interposer probe according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of intercepting signals between an expansion card and a computer's system board and transferring them to a logic analyzer module for analysis.